EP0988477B1 - Method and device for the power shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine - Google Patents

Method and device for the power shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine Download PDF

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Publication number
EP0988477B1
EP0988477B1 EP99908862A EP99908862A EP0988477B1 EP 0988477 B1 EP0988477 B1 EP 0988477B1 EP 99908862 A EP99908862 A EP 99908862A EP 99908862 A EP99908862 A EP 99908862A EP 0988477 B1 EP0988477 B1 EP 0988477B1
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EP
European Patent Office
Prior art keywords
switch
pressure
frequency
changeover
power
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Expired - Lifetime
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EP99908862A
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German (de)
French (fr)
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EP0988477A1 (en
Inventor
Horst Kohlmorgen
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CNH Industrial Baumaschinen GmbH
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O&K Orenstein and Koppel GmbH
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/42—Control of exclusively fluid gearing hydrostatic involving adjustment of a pump or motor with adjustable output or capacity
    • F16H61/423—Motor capacity control by fluid pressure control means
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H47/00—Combinations of mechanical gearing with fluid clutches or fluid gearing
    • F16H47/02—Combinations of mechanical gearing with fluid clutches or fluid gearing the fluid gearing being of the volumetric type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/68—Inputs being a function of gearing status
    • F16H2059/6838—Sensing gearing status of hydrostatic transmissions
    • F16H2059/6861—Sensing gearing status of hydrostatic transmissions the pressures, e.g. high, low or differential pressures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/14—Inputs being a function of torque or torque demand
    • F16H59/26—Inputs being a function of torque or torque demand dependent on pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/36—Inputs being a function of speed
    • F16H59/38—Inputs being a function of speed of gearing elements
    • F16H59/40—Output shaft speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/02—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used
    • F16H61/0202—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric
    • F16H61/0204—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal
    • F16H61/0213—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal characterised by the method for generating shift signals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/16—Inhibiting or initiating shift during unfavourable conditions, e.g. preventing forward reverse shift at high vehicle speed, preventing engine over speed

Definitions

  • the invention relates to a method and a device with the features according to the preamble of claim 1 or 9.
  • DE 195 20 454 C1 from the applicant is a method and a device for load-dependent automatic switching at least one two-stage hydraulic Drive motor of a mobile construction machine known in which by operating a switch at least two with at least a switching element in operative connection Pressure switches with different hydraulic response pressures can be activated one after the other, using depending on one or the other pressure switch specified load conditions in the hydraulic Drive circuit operated changeover valve on the changeover of the traction motor from its maximum swallowing volume lowest swallowing volume and vice versa effecting valve is controlled electrically.
  • This known method therefore concerns an automatic switchover of a two-stage hydraulic driving motor, however not a generic method in which a powershift transmission to be switched.
  • the object of the invention is a generic method and to further develop a generic device in such a way that depending on the load between the switching stages of the Powershift transmission automatically switched over in a reliable manner can be so that the entire driving range from minimal up to maximum speed at different Drive through driving resistances without manual switching can be.
  • driving safety should increase and a danger to the construction machine components during the switching process be safely avoided.
  • An automatic switchover is thus according to the invention provided by the driver by actuation a switch can be activated.
  • a switch can be activated.
  • a relay switching element or equivalent devices creates a switching window, which, on the one hand, automatically switches to both Directions (level 1 after level 2 and level 2 after level 1) enables and on the other hand unnecessarily frequent switching prevented. Switching is dependent hydrostatic pressure in the driving circuit (maximum or Minimum value).
  • the construction machine is monitored and exceeded a predetermined speed value Downshifting the powershift transmission is prevented.
  • a vehicle speed proportional Frequency signal from a Evaluation unit evaluated and via a frequency-dependent Switch enables or prevents switching becomes.
  • the frequency-dependent switch on the changeover valve acts.
  • the frequency-dependent switch acts on an additional valve, which is arranged parallel to the changeover valve and is hydraulically linked to it.
  • the driving speed the construction machine is monitored and at a standstill the construction machine automatically switches back the lowest gear of the powershift transmission takes place.
  • This can also expediently be via the frequency-dependent Switches are made via which are determined whether the vehicle is stationary or not. This can an additional frequency-dependent switch is also provided become.
  • that the lower response pressure of the pressure switch is set is that he has a pressure of the control pump in the area corresponds to their maximum output.
  • the upper response pressure the pressure switch is set so that it is in the range of the maximum system pressure.
  • the invention proposes to achieve the object stated at the outset also a device with the features of claim 9 before.
  • the switch is usually located in the cab the construction machine and makes the choice between manual and automatic switching.
  • the one with the pressure switches connected switching element can preferably be used as a relay be trained.
  • the frequency-dependent switch is advantageous in operative connection with the changeover valve.
  • you can but it should also be provided that the frequency-dependent Switch with an additional valve in operative connection is arranged in parallel to the switching valve and with this is hydraulically linked.
  • the frequency-dependent Switch has a first output that a relay with the changeover valve in operative connection stands.
  • this relay it is possible to control the frequency and thus speed-dependent switching only when reducing the speed, i.e. when downshifting of the powershift transmission to take effect to avoid a load-independent upshift. This ensures that the upshift only depends on the load he follows.
  • the frequency-dependent Switch has a second output that over another relay with the changeover valve in operative connection stands, with the further relay between the switching element and the switch and the relay arranged is.
  • the frequency-dependent switch can in the above Way have two outputs, alternatively can be provided that the frequency-dependent switch of two separate switches, each with an output is.
  • the pressure switch, the switching element, the frequency-dependent switch and the relays as common electronic, hydraulic or pneumatic Switching logic are formed.
  • An exemplary hydrostatic drive a mobile construction machine generally has one 2, 10 designated driving circuit and a connected to it Powershift transmission 1, which is shown in the Embodiment is two-stage, that is, a first and has a second gear.
  • the powershift transmission 1 has two output axes that drive the Steering axis and as a drive for the rigid axis of the construction machine serve.
  • the driving circuit 2, 10 has the usual elements that not explained in detail at this point.
  • a hydrostatic control pump is not shown, which is only indicated by an arrow 10.
  • in the Drive circuit 2, 10 is a hydraulic shuttle valve 11 arranged.
  • This hydraulic shuttle valve 11 About this hydraulic shuttle valve 11 are to the Driving circuit two parallel pressure switches 3 and 4 connected, which serve as switching elements and different have hydraulic response pressures. Both pressure switches 3 and 4 are designed as openers.
  • the pressure switch 3 has a smaller hydraulic response pressure on than the pressure switch 4.
  • Both pressure switches 3 and 4 are with a preferably formed by a relay Switching element 5 connected and with a switch 7, which is arranged in the cab of the construction machine.
  • This switching arrangement acts on a 4/2-way valve that hereinafter referred to as changeover valve 6.
  • changeover valve 6 is a changeover of the powershift transmission 1 from first gear to second gear or vice versa.
  • the switching arrangement also has a frequency-dependent Switch 9 on, which is connected to an initiator 8 is in the area of the rigid axis of the drive the construction machine is arranged or on another output side Location of the transmission can be arranged.
  • the frequency-dependent switch 9 has two outputs, the first output via a relay 12 with the switching valve 6 is connected.
  • the second output of the frequency dependent Switch 9 is connected via a relay 13 the switching valve 6 connected, the relay 13 between the switch valve 6 and the switch 7 in the cab as well as the relay 12 and the frequency-dependent Switch 9 is arranged.
  • the function of these components will be described in more detail below.
  • this is electrical pilot operated changeover valve 6 so that the first Gear is switched. They are in this state Pressure switches 3 and 4 closed. With the switch 7 in The driver's cab can choose between automatic in the closed position and fixed first gear in the open position.
  • the switch 9 works in its first switching output as a break contact if a specified Frequency signal dependent on vehicle speed by initiator 8 falls below a limit. Thereby can be used in fast moving mobile construction machines dangerous switching from higher to lower Prevent gear at impermissibly high driving speeds.
  • the relay 12 In series with the first output of the frequency dependent Switch 9 is the relay 12, which is electrically connected is that switching from the first to the second Gear only depending on the load pressure in the driving circuit and is not speed-dependent.
  • the hydraulic motor of the driving circuit 2 is swung out to Q max during the pressure increase (internal control in the driving circuit 2, 10), while the pump 10 is regulated back to a smaller delivery rate at its maximum power hyperbola.
  • the transmission output torque can due to a higher working pressure in the driving circuit 2, 10 and a larger absorption volume of the hydraulic motor following the driving force hyperbola (maximum power) increased to the maximum torque (gearbox output) be, whereby the driving speed decreases accordingly.
  • the pressure switch 3 is open at higher pressure. This means that no signal on the switching element 5 and the Switch 7 is given. At low pressure the Pressure switch 3 closed and there is a signal the switching element 5 and the switch 7.
  • the pressure switch 4 is closed below the maximum pressure P max and there is a voltage on the switching element 5.
  • the shift element 5 is in the first gear of the powershift transmission 1 open and closed in second gear.
  • the switch 7 can be opened or closed manually become. If it is open, the first gear is fixed, it is closed, the first or second gear is automatically connected.
  • the switch 9 has in the illustrated embodiment two outputs if the first output 9a (switching window) is open, the voltage is interrupted, there is a Circuit according to the logic of elements 3, 4, 5 and 7. Is the first output closed, a voltage is applied to that Relay 12 passed.
  • the relay 12 is open in the first gear and in the second Aisle closed.
  • the first gear switched and in the closed state is the first or the second gear, depending on the position of the Elements 12, 7 and 5.

Abstract

The invention relates to a method for the power shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine which comprises at least one hydrostatic variable capacity pump, a hydrostatic drive motor and a two-stage powershift transmission. The axle(s) of the construction machine is/are driven by the drive shaft of said powershift transmission. The powershift transmission is shifted via a change-over valve. The invention provides a method which enables the load-dependency between the shifting steps of the powershift transmission to be automatically changed over in an operationally reliable manner. In order to automatically change over the powershift transmission (1) in a load-dependent manner by the actuation of a switch (7), at least two pressure switches (3, 4), said switches interacting with at least one switch element (5), are actuated in succession by different hydraulic operating pressures. The switch element (5) is actuated by one or the other pressure switch (3, 4) according to predetermined load states in the hydraulic drive circuit. Said switch element electrically controls the change-over valve (6) for enacting a change-over of the powershift transmission (1).

Description

Die Erfindung betrifft ein Verfahren bzw. eine Einrichtung mit den Merkmalen gemäß Oberbegriff des Patentanspruchs 1 bzw. 9.The invention relates to a method and a device with the features according to the preamble of claim 1 or 9.

Es sind Mobilbagger oder vergleichbare Baumaschinen entsprechend den Merkmalen des jeweiligen Oberbegriffs mit manuell schaltbaren zweistufigen Stirnradgetrieben in Verbindung mit einem hydrostatischen Fahrantrieb oder mit einem rein hydrostatischen Fahrantrieb (Hydrotransmatik) bekannt. Das Schalten geschieht entweder durch manuellen Eingriff des Fahrers auf die Getriebeschaltung oder durch automatische oder manuelle Schaltvorgänge im hydrostatischen Fahrantrieb.They are mobile excavators or comparable construction machines according to the characteristics of the respective generic term manually switchable two - stage spur gear in Connection with a hydrostatic drive or with a purely hydrostatic drive (hydrotransmatics) known. Switching is done either manually Intervention of the driver on the gear shift or by automatic or manual switching operations in hydrostatic Traction drive.

Beim manuellen Schalten des Getriebes ist nicht auszuschließen, daß der Fahrantrieb nicht in der optimalen Schaltstufe betrieben wird. Dies kann im ungünstigsten Fall sogar die Fahrsicherheit und auch die Komponenten der Baumaschine gefährden, beispielsweise, wenn ein Umschalten in einen niedrigen Gang bei zu hoher Fahrgeschwindigkeit erfolgt.When switching the transmission manually, it cannot be ruled out that the travel drive is not in the optimal Switching stage is operated. This can be the worst Case even driving safety and also the components endanger the construction machine, for example, when switching in a low gear when the driving speed is too high he follows.

Aus DE 195 20 454 C1 der Anmelderin ist ein Verfahren und eine Einrichtung zur lastabhängigen automatischen Umschaltung wenigstens eines zweistufigen hydraulischen Fahrmotors einer mobilen Baumaschine bekannt, bei dem durch Betätigung eines Schalters mindestens zwei mit mindestens einem Schaltelement in Wirkverbindung stehende Druckschalter mit unterschiedlichen hydraulischen Ansprechdrücken nacheinander aktiviert werden, wobei über das von dem einen oder dem anderen Druckschalter in Abhängigkeit vorgegebener Lastzustände im hydraulischen Fahrkreis betätigte Umschaltventil ein die Umschaltung des Fahrmotors von seinem größten Schluckvolumen auf sein geringstes Schluckvolumen und umgekehrt bewirkendes Ventil elektrisch angesteuert wird. Dieses bekannte Verfahren betrifft somit eine automatische Umschaltung eines zweistufigen hyraulischen Fahrmotors, betrifft jedoch kein gattungsgemäßes Verfahren, bei dem ein Lastschaltgetriebe umgeschaltet werden soll.DE 195 20 454 C1 from the applicant is a method and a device for load-dependent automatic switching at least one two-stage hydraulic Drive motor of a mobile construction machine known in which by operating a switch at least two with at least a switching element in operative connection Pressure switches with different hydraulic response pressures can be activated one after the other, using depending on one or the other pressure switch specified load conditions in the hydraulic Drive circuit operated changeover valve on the changeover of the traction motor from its maximum swallowing volume lowest swallowing volume and vice versa effecting valve is controlled electrically. This known method therefore concerns an automatic switchover of a two-stage hydraulic driving motor, however not a generic method in which a powershift transmission to be switched.

Aufgabe der Erfindung ist es, ein gattungsgemäßes Verfahren und eine gattungsgemäße Einrichtung derart weiterzubilden, daß lastabhängig zwischen den Schaltstufen des Lastschaltgetriebes betriebssicher automatisch umgeschaltet werden kann, so daß der gesamte Fahrbereich von Minimal- bis Höchstgeschwindigkeit bei unterschiedlichen Fahrwiderständen ohne manuelles Umschalten durchfahren werden kann. Außerdem soll die Fahrsicherheit erhöht und eine Gefährdung der Baumaschinenkomponenten beim Schaltvorgang sicher vermieden werden.The object of the invention is a generic method and to further develop a generic device in such a way that depending on the load between the switching stages of the Powershift transmission automatically switched over in a reliable manner can be so that the entire driving range from minimal up to maximum speed at different Drive through driving resistances without manual switching can be. In addition, driving safety should increase and a danger to the construction machine components during the switching process be safely avoided.

Diese Aufgabe wird mit einem Verfahren der eingangs bezeichneten Art erfindungsgemäß durch die kennzeichnenden Merkmale des Patentanspruchs 1 gelöst. This task is carried out using a method of the type mentioned at the beginning Kind according to the invention by the characteristic Features of claim 1 solved.

Erfindungsgemäß wird somit eine automatische Umschaltung zur Verfügung gestellt, die vom Fahrer durch Betätigung eines Schalters aktivierbar ist. Dabei wird mit Hilfe von zwei Druckschaltern und einem Relais (Schaltelement) oder gleichwirkenden Einrichtungen ein Schaltfenster erzeugt, welches zum einen das automatische Umschalten in beide Richtungen (Stufe 1 nach Stufe 2 und Stufe 2 nach Stufe 1) ermöglicht und andererseits unnötig häufiges Umschalten verhindert. Das Umschalten erfolgt in Abhängigkeit vom hydrostatischen Druck im Fahrkreis (Maximal- oder Minimalwert).An automatic switchover is thus according to the invention provided by the driver by actuation a switch can be activated. With the help of two pressure switches and a relay (switching element) or equivalent devices creates a switching window, which, on the one hand, automatically switches to both Directions (level 1 after level 2 and level 2 after level 1) enables and on the other hand unnecessarily frequent switching prevented. Switching is dependent hydrostatic pressure in the driving circuit (maximum or Minimum value).

Zur Erhöhung der Fahrsicherheit und der Sicherheit der Maschinenkomponenten beim Umschalten ist erfindungsgemäß vorgesehen, daß die Fahrgeschwindigkeit der Baumaschine überwacht und bei Überschreiten eines vorgegebenen Geschwindigkeitswertes ein Zurückschalten des Lastschaltgetriebes verhindert wird. Dies läßt sich besonders vorteilhaft dadurch erreichen, daß zur Überwachung der Fahrgeschwindigkeit ein fahrgeschwindigkeitsproportionales Frequenzsignal von einer Auswerteeinheit bewertet und über einen frequenzabhängigen Schalter das Umschalten ermöglicht oder verhindert wird.To increase driving safety and the safety of the Machine components when switching According to the invention provided that the driving speed the construction machine is monitored and exceeded a predetermined speed value Downshifting the powershift transmission is prevented. This can be achieved particularly advantageously by that to monitor the vehicle speed a vehicle speed proportional Frequency signal from a Evaluation unit evaluated and via a frequency-dependent Switch enables or prevents switching becomes.

Ein unproblematisches Umschalten in eine niedrige Schaltstufe ist deshalb immer nur dann möglich, wenn die Fahrgeschwindigkeit der Baumaschine dies unproblematisch zuläßt. Dazu wird ein fahrgeschwindigkeitsproportionales Frequenzsignal (Tachometersignal) von einer entsprechenden Einheit bewertet. Nur wenn die Fahrgeschwindigkeit (Frequenz) innerhalb eines vorgegebenen Schaltfensters liegt, kann eine Umschaltung erfolgen.An unproblematic switch to a low switching level is therefore only possible if the driving speed the construction machine allows this without problems. For this, a driving speed proportional Frequency signal (tachometer signal) from a corresponding Unit rated. Only if the driving speed (Frequency) within a given switching window a switch can be made.

Vorzugsweise ist verfahrensmäßig weiterhin vorgesehen, daß der frequenzabhängige Schalter auf das Umschaltventil einwirkt. Alternativ kann auch vorgesehen sein, daß der frequenzabhängige Schalter auf ein zusätzliches Ventileinwirkt, welches parallel zum Umschaltventil angeordnet und mit diesem hydraulisch verknüpft ist.In terms of the method, it is preferably also provided that that the frequency-dependent switch on the changeover valve acts. Alternatively, it can also be provided that the frequency-dependent switch acts on an additional valve, which is arranged parallel to the changeover valve and is hydraulically linked to it.

Ferner ist vorteilhaft vorgesehen, daß das Hochschalten des Lastschaltgetriebes ausschließlich lastabhängig über die Druckschalter erfolgt. Dazu ist der frequenzabhängige Schalter über geeignete Elemente, beispielsweise Relais, mit dem Umschaltventil zu verbinden, um die frequenzabhängige Schaltung so einzurichten, daß sie nur für das Herunterschalten wirksam ist.It is also advantageously provided that the upshift of the powershift transmission only depending on the load the pressure switch is done. This is the frequency dependent Switches via suitable elements, such as relays, to connect with the changeover valve to the frequency dependent Set up circuit so that it is only for that Downshift is effective.

Weiterhin ist vorteilhaft vorgesehen, daß die Fahrgeschwindigkeit der Baumaschine überwacht und bei Stillstand der Baumaschine automatisch eine Rückschaltung in den niedrigsten Gang des Lastschaltgetriebes erfolgt. Dies kann zweckmäßigerweise ebenfalls über den frequenzabhängigen Schalter erfolgen, über den festgestellt werden kann, ob das Fahrzeug steht oder nicht. Hierzu kann auch ein zusätzlicher frequenzabhängiger Schalter vorgesehen werden.It is also advantageously provided that the driving speed the construction machine is monitored and at a standstill the construction machine automatically switches back the lowest gear of the powershift transmission takes place. This can also expediently be via the frequency-dependent Switches are made via which are determined whether the vehicle is stationary or not. This can an additional frequency-dependent switch is also provided become.

In weiterer vorteilhafter Ausgestaltung ist vorgesehen, daß der untere Ansprechdruck der Druckschalter so eingestellt wird, daß er einem Druck der Regelpumpe im Bereich ihrer maximalen Fördermenge entspricht.In a further advantageous embodiment, that the lower response pressure of the pressure switch is set is that he has a pressure of the control pump in the area corresponds to their maximum output.

Ferner ist verfahrensmäßig vorgesehen, daß der obere Ansprechdruck der Druckschalter so eingestellt wird, daß er im Bereich des maximalen Systemdruckes liegt.It is also procedurally provided that the upper response pressure the pressure switch is set so that it is in the range of the maximum system pressure.

Zur Lösung der eingangs gestellten Aufgabe schlägt die Erfindung auch eine Einrichtung mit den Merkmalen des Patentanspruchs 9 vor. The invention proposes to achieve the object stated at the outset also a device with the features of claim 9 before.

Der Schalter befindet sich üblicherweise im Fahrerhaus der Baumaschine und bewirkt die Wahl zwischen manueller und automatischer Schaltung. Das mit den Druckschaltern verbundene Schaltelement kann vorzugsweise als Relais ausgebildet sein.The switch is usually located in the cab the construction machine and makes the choice between manual and automatic switching. The one with the pressure switches connected switching element can preferably be used as a relay be trained.

Vorteilhaft steht dabei der frequenzabhängige Schalter mit dem Umschaltventil in Wirkverbindung. Alternativ kann aber auch vorgesehen sein, daß der freguenzabhängige Schalter mit einem zusätzlichen Ventil in Wirkverbindung steht, das parallel zum Umschaltventil angeordnet und mit diesem hydraulisch verknüpft ist.The frequency-dependent switch is advantageous in operative connection with the changeover valve. Alternatively, you can but it should also be provided that the frequency-dependent Switch with an additional valve in operative connection is arranged in parallel to the switching valve and with this is hydraulically linked.

Besonders vorteilhaft ist vorgesehen, daß der frequenzabhängige Schalter einen ersten Ausgang aufweist, der über ein Relais mit dem Umschaltventil in Wirkverbindung steht. Über dieses Relais ist es möglich, das frequenzund damit geschwindigkeitsabhängige Schalten nur bei Verringerung der Geschwindigkeit, d.h. beim Herunterschalten des Lastschaltgetriebes, wirksam werden zu lassen, um zu vermeiden, daß ein lastunabhängiges Hochschalten erfolgt. Damit ist gewährleistet, daß das Hochschalten nur lastabhängig erfolgt.It is particularly advantageous that the frequency-dependent Switch has a first output that a relay with the changeover valve in operative connection stands. With this relay it is possible to control the frequency and thus speed-dependent switching only when reducing the speed, i.e. when downshifting of the powershift transmission to take effect to avoid a load-independent upshift. This ensures that the upshift only depends on the load he follows.

Weiterhin ist vorteilhaft vorgesehen, daß der frequenzabhängige Schalter einen zweiten Ausgang aufweist, der über ein weiteres Relais mit dem Umschaltventil in Wirkverbindung steht, wobei das weitere Relais zwischen dem Umschaltelement und dem Schalter sowie dem Relais angeordnet ist. Durch das Vorsehen dieses weiteren Relais ist es möglich, automatisch bei Stillstand des Fahrzeuges eine Schaltung in den ersten Gang zu bewirken.It is also advantageously provided that the frequency-dependent Switch has a second output that over another relay with the changeover valve in operative connection stands, with the further relay between the switching element and the switch and the relay arranged is. By providing this additional relay it is possible, automatically when the vehicle is at a standstill To effect circuit in first gear.

Der frequenzabhängige Schalter kann in der vorbeschriebenen Weise zwei Ausgänge aufweisen, alternativ kann auch vorgesehen sein, daß der frequenzabhängige Schalter von zwei getrennten Schältern mit jeweils einem Ausgang gebildet ist.The frequency-dependent switch can in the above Way have two outputs, alternatively can be provided that the frequency-dependent switch of two separate switches, each with an output is.

Anstelle der vorbeschriebenen einzelnen Bauelemente kann auch vorgesehen sein, daß die Druckschalter, das Schaltelement, der frequenzabhängige Schalter und die Relais als gemeinsame elektronische, hydraulische oder pneumatische Schaltlogik ausgebildet sind.Instead of the individual components described above also be provided that the pressure switch, the switching element, the frequency-dependent switch and the relays as common electronic, hydraulic or pneumatic Switching logic are formed.

Die Erfindung ist nachstehend anhand der Zeichnung beispielsweise näher erläutert. Diese zeigt in:

Fig. 1
eine Prinzipskizze eines Funktionsplanes zur automatischen Umschaltung eines zweistufigen Lastschaltgetriebes eines hydrostatischen Fahrantriebes einer mobilen Baumaschine und
Fig. 2
ein Flußdiagramm zur Verdeutlichung der Schaltvorgänge.
The invention is explained below with reference to the drawing, for example. This shows in:
Fig. 1
a schematic diagram of a function plan for the automatic switching of a two-stage powershift transmission of a hydrostatic travel drive of a mobile construction machine and
Fig. 2
a flowchart to illustrate the switching operations.

Ein beispielhaft dargestellter hydrostatischer Fahrantrieb einer mobilen Baumaschine weist einen allgemein mit 2, 10 bezeichneten Fahrkreis und ein mit diesem verbundenes Lastschaltgetriebe 1 auf, welches beim dargestellten Ausführungsbeispiel zweistufig ist, also einen ersten und einen zweiten Gang aufweist. Das Lastschaltgetriebe 1 weist zwei Abtriebsachsen auf, die als Antrieb für die Lenkachse und als Antrieb für die Starrachse der Baumaschine dienen. An exemplary hydrostatic drive a mobile construction machine generally has one 2, 10 designated driving circuit and a connected to it Powershift transmission 1, which is shown in the Embodiment is two-stage, that is, a first and has a second gear. The powershift transmission 1 has two output axes that drive the Steering axis and as a drive for the rigid axis of the construction machine serve.

Der Fahrkreis 2, 10 weist die üblichen Elemente auf, die im einzelnen an dieser Stelle nicht näher erläutert werden. Nicht dargestellt ist eine hydrostatische Regelpumpe, die nur durch einen Pfeil 10 angedeutet ist. Im Fahrkreis 2, 10 ist ein hydraulisches Wechselventil 11 angeordnet.The driving circuit 2, 10 has the usual elements that not explained in detail at this point. A hydrostatic control pump is not shown, which is only indicated by an arrow 10. in the Drive circuit 2, 10 is a hydraulic shuttle valve 11 arranged.

Über dieses hydraulische Wechselventil 11 sind an den Fahrkreis zwei parallele Druckschalter 3 und 4 angeschlossen, die als Schaltelemente dienen und unterschiedliche hydraulische Ansprechdrücke aufweisen. Beide Druckschalter 3 und 4 sind als Öffner ausgebildet. Der Druckschalter 3 weist einen kleineren hydraulischen Ansprechdruck auf als der Druckschalter 4. Beide Druckschalter 3 und 4 sind mit einem vorzugsweise von einem Relais gebildeten Schaltelement 5 verbunden sowie mit einem Schalter 7, der im Fahrerhaus der Baumaschine angeordnet ist. Diese Schaltanordnung wirkt auf ein 4/2-Wegeventil, das nachfolgend als Umschaltventil 6 bezeichnet wird. Mit diesem Umschaltventil 6 ist ein Umschalten des Lastschaltgetriebes 1 vom ersten Gang in den zweiten Gang oder umgekehrt möglich.About this hydraulic shuttle valve 11 are to the Driving circuit two parallel pressure switches 3 and 4 connected, which serve as switching elements and different have hydraulic response pressures. Both pressure switches 3 and 4 are designed as openers. The pressure switch 3 has a smaller hydraulic response pressure on than the pressure switch 4. Both pressure switches 3 and 4 are with a preferably formed by a relay Switching element 5 connected and with a switch 7, which is arranged in the cab of the construction machine. This switching arrangement acts on a 4/2-way valve that hereinafter referred to as changeover valve 6. With this changeover valve 6 is a changeover of the powershift transmission 1 from first gear to second gear or vice versa.

Die Schaltanordnung weist darüber hinaus einen frequenzabhängigen Schalter 9 auf, der mit einem Initiator 8 verbunden ist, der im Bereich der Starrachse des Antriebes der Baumaschine angeordnet ist oder an einem anderen abtriebsseitigen Ort des Getriebes angeordnet sein kann.The switching arrangement also has a frequency-dependent Switch 9 on, which is connected to an initiator 8 is in the area of the rigid axis of the drive the construction machine is arranged or on another output side Location of the transmission can be arranged.

Der frequenzabhängige Schalter 9 weist zwei Ausgänge auf, wobei der erste Ausgang über ein Relais 12 mit dem Umschaltventil 6 verbunden ist. Der zweite Ausgang des frequenzabhängigen Schalters 9 ist über ein Relais 13 mit dem Umschaltventil 6 verbunden, wobei das Relais 13 zwischen dem Umschaltventil 6 und dem Schalter 7 im Fahrerhaus sowie dem Relais 12 und dem frequenzabhängigen Schalter 9 angeordnet ist. Die Funktion dieser Bauelemente wird nachfolgend noch näher beschrieben.The frequency-dependent switch 9 has two outputs, the first output via a relay 12 with the switching valve 6 is connected. The second output of the frequency dependent Switch 9 is connected via a relay 13 the switching valve 6 connected, the relay 13 between the switch valve 6 and the switch 7 in the cab as well as the relay 12 and the frequency-dependent Switch 9 is arranged. The function of these components will be described in more detail below.

Im dargestellten stromlosen Ruhezustand steht das elektrisch vorgesteuerte Umschaltventil 6 so, daß der erste Gang geschaltet ist. In diesem Zustand sind die beiden Druckschalter 3 und 4 geschlossen. Mit dem Schalter 7 im Fahrerhaus kann eine Wahl getroffen werden zwischen Automatik in geschlossener Stellung und fixiertem ersten Gang in geöffneter Position.In the currentless idle state shown, this is electrical pilot operated changeover valve 6 so that the first Gear is switched. They are in this state Pressure switches 3 and 4 closed. With the switch 7 in The driver's cab can choose between automatic in the closed position and fixed first gear in the open position.

Unabhängig von der Schalterstellung 7 bewirkt das weitere Relais 13 ein Umschalten in den ersten Gang durch Öffnen im Stillstand der Baumaschine. Im folgenden wird der Zustand "Automatik" beschrieben: Regardless of switch position 7, this has the effect Relay 13 switches to first gear by opening with the construction machine at a standstill. The following is the state "Automatic" described:

Das Anfahren aus dem Stillstand erfolgt immer im ersten Gang, weil das im Stillstand geöffnete Relais 13 dieses bewirkt. Bei Geschwindigkeiten größer als 0 wird lastdruckabhängig ggf. in den 2. Gang geschaltet.Starting from standstill always takes place in the first Gear, because the relay 13 open at standstill this causes. At speeds greater than 0, the load pressure is dependent if necessary, switched to 2nd gear.

Solange im 2. Gang ein Druck im Fahrkreis 2, 10 auftritt, der niedriger ist als der Ansprechdruck des Druckschalters 3 sind beide Druckschalter 3 und 4 und das Schaltelement 5 geschlossen und der zweite Gang bleibt geschaltet. Steigt der Druck im Fahrkreis 2, 10, wobei je nach Fahrrichtung der jeweils höhere Druck im Fahrkreis über das Wechselventil 11 an den Druckschaltern 3 und 4 anliegt, so öffnet zuerst der Druckschalter 3, was aber noch keine Auswirkung hat, und bei Erreichen eines entsprechend höheren Druckes auch der Druckschalter 4. Dies bewirkt jetzt, daß das Schaltelement 5 öffnet und damit ein Signal zum Schalten in den ersten Gang gibt. Der erste Gang wird allerdings durch Umschalten des Umschaltventiles 6 nur dann geschaltet, wenn auch der frequenzabhängige Schalter 9 geöffnet ist. Der Schalter 9 arbeitet in seinem ersten Schaltausgang als Öffner, wenn ein vorgegebenes, fahrgeschwindigkeitsabhängiges Frequenzsignal vom Initiator 8 einen Grenzwert unterschreitet. Dadurch läßt sich bei schnell fahrenden mobilen Baumaschinen ein gefährliches Umschalten vom höheren in einen niedrigen Gang bei unzulässig hoher Fahrgeschwindigkeit verhindern. As long as there is pressure in 2nd gear 10 in 2nd gear, which is lower than the response pressure of the pressure switch 3 are both pressure switches 3 and 4 and the switching element 5 closed and the second gear remains engaged. The pressure in the driving circuit 2, 10 increases, depending on Direction of travel the higher pressure in the driving circuit the shuttle valve 11 is applied to the pressure switches 3 and 4, so the pressure switch 3 opens first, but what has no effect yet, and when one is reached accordingly higher pressure also the pressure switch 4. This now causes the switching element 5 to open and thus gives a signal to shift into first gear. The First gear is, however, by switching the switch valve 6 only switched if the frequency-dependent Switch 9 is open. The switch 9 works in its first switching output as a break contact if a specified Frequency signal dependent on vehicle speed by initiator 8 falls below a limit. Thereby can be used in fast moving mobile construction machines dangerous switching from higher to lower Prevent gear at impermissibly high driving speeds.

Gleichermaßen wird dadurch auch ein manuelles Umschalten in den ersten Gang verhindert.Likewise, this also makes manual switching prevented in the first gear.

In Reihe zu dem ersten Ausgang des frequenzabhängigen Schalters 9 liegt das Relais 12, das so elektrisch verschaltet ist, daß ein Umschalten vom ersten in den zweiten Gang nur in Abhängigkeit vom Lastdruck im Fahrkreis und nicht geschwindigkeitsabhängig erfolgt.In series with the first output of the frequency dependent Switch 9 is the relay 12, which is electrically connected is that switching from the first to the second Gear only depending on the load pressure in the driving circuit and is not speed-dependent.

Der Hydromotor des Fahrkreises 2 wird während des Druckanstieges auf Qmax ausgeschwenkt (innere Regelung im Fahrkreis 2, 10), während die Pumpe 10 auf ihrer maximalen Leistungshyperbel auf eine kleinere Fördermenge zurückgeregelt wird.The hydraulic motor of the driving circuit 2 is swung out to Q max during the pressure increase (internal control in the driving circuit 2, 10), while the pump 10 is regulated back to a smaller delivery rate at its maximum power hyperbola.

Für die gleiche Fahrgeschwindigkeit im ersten Gang, wie vor dem Umschalten im zweiten Gang geht die Hauptpumpe (Fahren) aufgrund des fallenden hydraulischen Arbeitsdruckes wieder auf eine höhere Fördermenge und der hydrostatische Fahrmotor auf ein kleines Schluckvolumen.For the same driving speed in first gear as the main pump switches before switching to second gear (Driving) due to the falling hydraulic working pressure again to a higher flow rate and the hydrostatic Traction motor to a small swallowing volume.

Dabei fließt trotz des niedrigeren hydraulischen Arbeitsdruckes und des verringerten Schluckvolumens des Hydromotors aufgrund der geänderten Getriebeübersetzung annähernd das gleiche Getriebeabtriebsmoment zu den Achsen. It flows despite the lower hydraulic working pressure and the reduced swallowing volume of the hydraulic motor due to the changed gear ratio the same transmission output torque to the axes.

Bei weiter steigendem Fahrwiderstand kann das Getriebeabtriebsmoment durch einen höheren Arbeitsdruck im Fahrkreis 2, 10 und ein größeres Schluckvolumen des Hydromotors der Triebkrafthyperbel folgend (maximale Leistung) bis zum maximalen Drehmoment (Getriebeabtrieb) gesteigert werden, wobei die Fahrgeschwindigkeit entsprechend zurückgeht.If the driving resistance continues to increase, the transmission output torque can due to a higher working pressure in the driving circuit 2, 10 and a larger absorption volume of the hydraulic motor following the driving force hyperbola (maximum power) increased to the maximum torque (gearbox output) be, whereby the driving speed decreases accordingly.

Verringert sich der Fahrwiderstand und damit der Druck im Fahrkreis wieder, so schließt als erstes der Druckschalter 4. Dies hat aber aufgrund der elektrischen Verschaltung noch keinen Einfluß, da das Schaltelement 5 elektrisch noch unversorgt bleibt (erster Gang bleibt geschaltet). Erst beim Erreichen des Schaltdruckes des Druckschalters 3 wird das Schaltelement 5 mit elektrischer Spannung versorgt und schließt. Dies hat zur Folge, daß das Umschaltventil 6 umschaltet und ein Schaltvorgang in die zweite Getriebestufe (zweiter Gang) erfolgt. Die geänderte Getriebeübersetzung bewirkt einen höheren Druck im Fahrkreis, der wiederum eine Anpassung des Schluckvolumens der Fahrpumpe 10 zur Folge hat. Bei weiter fallendem Fahrwiderstand folgt der hydrostatische Fahrantrieb der Triebkrafthyperbel bei maximaler Antriebsleistung bis zur Höchstgeschwindigkeit.The driving resistance and thus the pressure in the vehicle are reduced Again, the pressure switch closes first 4. But this has due to the electrical connection still no influence, since the switching element 5 is electrical remains unupplied (first gear remains engaged). Only when the switching pressure of the Pressure switch 3, the switching element 5 with electrical Power supplies and closes. As a consequence, that the switching valve 6 switches and a switching operation in the second gear stage (second gear). The changed gear ratio causes a higher pressure in the driving circuit, which in turn adjusts the swallowing volume the driving pump 10 has the consequence. If it continues to fall Driving resistance follows the hydrostatic drive the driving force hyperbole with maximum drive power up to to top speed.

Der vorbeschriebene Funktionsablauf ist auch im Flußdiagramm der Figur 2 dargestellt, aus dem die einzelnen Schaltbedingungen genauer zu entnehmen sind. Dabei sind dieselben Bezugszeichen wie in Figur 1 verwandt, lediglich der erste Ausgang des Schalters 9 ist mit 9a bezeichnet und der zweite Ausgang mit 9b. Die elektrische Spannung ist mit der üblichen Bezeichnung U, die Frequenz mit F und der Druck mit P bezeichnet.The functional sequence described above is also in the flow chart shown in Figure 2, from which the individual Switching conditions can be found more precisely. Are there the same reference numerals as used in Figure 1, only the first output of the switch 9 is designated 9a and the second exit with 9b. The electrical Voltage is commonly called U, the frequency with F and the pressure with P.

Aus den Figuren 1 und 2 geht für die einzelnen Elemente jeweils folgende Schaltstellung hervor:Figures 1 and 2 go for the individual elements the following switch position:

Der Druckschalter 3 ist bei höherem Druck geöffnet. Dies bedeutet, daß kein Signal auf das Schaltelement 5 und den Schalter 7 gegeben wird. Bei niedrigem Druck ist der Druckschalter 3 geschlossen und es gibt ein Signal auf das Schaltelement 5 und den Schalter 7.The pressure switch 3 is open at higher pressure. This means that no signal on the switching element 5 and the Switch 7 is given. At low pressure the Pressure switch 3 closed and there is a signal the switching element 5 and the switch 7.

Der Druckschalter 4 ist unterhalb des Maximaldruckes Pmax geschlossen und es liegt eine Spannung am Schaltelement 5 an.The pressure switch 4 is closed below the maximum pressure P max and there is a voltage on the switching element 5.

Das Schaltelement 5 ist im ersten Gang des Lastschaltgetriebes 1 offen und im zweiten Gang geschlossen.The shift element 5 is in the first gear of the powershift transmission 1 open and closed in second gear.

Der Schalter 7 kann manuell geöffnet oder geschlossen werden. Ist er offen, ist der erste Gang fixiert, ist er geschlossen, wird automatisch der erste oder zweite Gang geschaltet.The switch 7 can be opened or closed manually become. If it is open, the first gear is fixed, it is closed, the first or second gear is automatically connected.

Der Schalter 9 hat beim dargestellten Ausführungsbeispiel zwei Ausgänge, wenn der erste Ausgang 9a (Schaltfenster) offen ist, ist die Spannung unterbrochen, es erfolgt eine Schaltung gemäß der Logik der Elemente 3, 4, 5 und 7. Ist der erste Ausgang geschlossen, wird eine Spannung an das Relais 12 geleitet.The switch 9 has in the illustrated embodiment two outputs if the first output 9a (switching window) is open, the voltage is interrupted, there is a Circuit according to the logic of elements 3, 4, 5 and 7. Is the first output closed, a voltage is applied to that Relay 12 passed.

Wenn der zweite Ausgang 9b des Schalters 9 offen ist (bei Frequenz 0) liegt kein Schaltsignal am Relais 13 (wie dargestellt). Der zweite Ausgang 9b ist geschlossen bei einer Frequenz größer 0, was bedeutet, daß ein Schaltsignal an das Relais 13 geliefert wird.If the second output 9b of the switch 9 is open (at Frequency 0) there is no switching signal at relay 13 (like ) Shown. The second outlet 9b is closed at a frequency greater than 0, which means that a switching signal is delivered to the relay 13.

Das Relais 12 ist im ersten Gang offen und im zweiten Gang geschlossen.The relay 12 is open in the first gear and in the second Aisle closed.

Ist das weitere Relais 13 offen, so ist der erste Gang geschaltet und im geschlossenen Zustand ist der erste oder der zweite Gang geschaltet, je nach Stellung der Elemente 12, 7 und 5.If the further relay 13 is open, then the first gear switched and in the closed state is the first or the second gear, depending on the position of the Elements 12, 7 and 5.

Claims (15)

  1. Method for the power-shiftable changeover of a hydrostatic vehicle drive of a mobile construction machine that has at least one hydrostatic variable-capacity pump, an automatically regulated hydrostatic propelling motor and a not less than two-stage power-shift transmission (1) which via its output shaft drives the axles of the construction machine, the power-shift transmission being operated pneumatically, by hydraulic pressure or by electrical voltage, via at least one changeover valve (6),
    characterised in that for the load-dependent automatic changeover of the power-shift transmission (1) by the operation of a switch (7), at least two pressure switches (3, 4) operatively connected to at least one switch element (5) and responding at different hydraulic pressures are operated one after the other, the switch element (5) being operated by one or the other pressure switch (3, 4) in dependence on preset load states in the hydraulic propulsion circuit, and said switch element (5) energising the changeover valve (6) so as to effect the changeover of the power-shift transmission (1), the travelling speed of the construction machine being monitored and the power-shift transmission (1) being prevented from re-engaging in the event that a preset speed level is exceeded.
  2. Method according to claim 1,
    characterised in that for monitoring the travelling speed, an evaluator assesses a frequency signal proportional to the travelling speed and a frequency-dependent switch (9) enables or prevents the changeover.
  3. Method according to claim 2,
    characterised in that the frequency-dependent switch (9) acts on the changeover valve (6).
  4. Method according to claim 2,
    characterised in that the frequency-dependent switch (9) acts on an additional valve which is disposed parallel to the changeover valve (6) and is hydraulically linked thereto.
  5. Method according to claim 2, 3 or 4,
    characterised in that upshifting of the power-shift transmission (1) takes place in an exclusively load-dependent manner via the pressure switches (3, 4).
  6. Method according to claim 1 or any of those following,
    characterised in that the travelling speed of the construction machine is monitored and when the construction machine is stationary the lowest gear of the power-shift transmission (1) is automatically reengaged.
  7. Method according to claim 1 or any of those following,
    characterised in that the lower response pressure of the pressure switches (3, 4) is set so as to correspond to a variable-capacity pump pressure in the region of its maximum capacity.
  8. Method according to claim 1 or any of those following,
    characterised in that the upper response pressure of the pressure switches (3, 4) is set so as to be in the region of the maximum system pressure.
  9. Device for the power-shiftable changeover of a hydrostatic vehicle drive of a mobile construction machine that has at least one hydrostatic variable-capacity pump, an automatically regulated hydrostatic propelling motor and a not less than two-stage power-shift transmission (1) which via its output shaft drives the axles of the construction machine, the power-shift transmission being adapted to be operated pneumatically, by hydraulic pressure or by electrical voltage via at least one changeover valve (6),
    characterised in that for the load-dependent automatic changeover of the power-shift transmission (1) a switch (7) and at least two pressure switches (3, 4) responding at different hydraulic response pressures, the pressure switches (3, 4) being operatively connected to a switch element (5) which is connected to the changeover valve (6) and energises the latter, there being provided an evaluator for monitoring the travelling speed and, connected thereto, a frequency-dependent switch (9) which enables or prevents the changeover of the power-shift transmission (1).
  10. Device according to claim 9,
    characterised in that the frequency-dependent switch (9) is operatively connected to the changeover switch (6).
  11. Device according to claim 9,
    characterised in that the frequency-dependent switch (9) is operatively connected to an additional valve that is disposed parallel to the changeover valve (6) and is hydraulically linked thereto.
  12. Device according to claim 10,
    characterised in that the frequency-dependent switch (9) has a first output which is operatively connected to the changeover valve (6) via a relay (12).
  13. Device according to claim 12,
    characterised in that the frequency-dependent switch (9) has a second output which is operatively connected to the changeover valve (6) via a further relay (13), the further relay (13) being arranged between the changeover element (6) and the switch (7) and the relay (12).
  14. Device according to claim 13,
    characterised in that the frequency-dependent switch (9) is constituted by two separate switches with a respective output in each case.
  15. Device according to claim 9 or any of those following,
    characterised in that the pressure switches (3, 4), the switch element (5), the frequency-dependent switch (9) and the relays (12, 13) are configured as a common electronic, hydraulic or pneumatic switching logic system.
EP99908862A 1998-03-27 1999-02-09 Method and device for the power shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine Expired - Lifetime EP0988477B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19813622 1998-03-27
DE19813622A DE19813622C2 (en) 1998-03-27 1998-03-27 Method and device for power switchable switching of a hydrostatic travel drive of a mobile construction machine
PCT/EP1999/000823 WO1999050575A1 (en) 1998-03-27 1999-02-09 Method and device for the power shiftable change-over of a hydrostatic vehicle drive of a mobile construction machine

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EP0988477B1 true EP0988477B1 (en) 2002-12-18

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WO1999050575A1 (en) 1999-10-07
US6401856B1 (en) 2002-06-11
DE19813622C2 (en) 2002-01-10
KR100654074B1 (en) 2006-12-07
EP0988477A1 (en) 2000-03-29
JP4499191B2 (en) 2010-07-07
JP2002500741A (en) 2002-01-08
KR20010012984A (en) 2001-02-26
DE19813622A1 (en) 1999-10-07
BR9904892A (en) 2000-09-19

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